Substrate processing apparatus, substrate processing method, semiconductor device manufacturing method, and control program

ABSTRACT

The present disclosure provides a substrate processing apparatus, a substrate processing method, a semiconductor device manufacturing method, and a control program capable of controlling thickness uniformity of a film formed on a substrate. The substrate processing apparatus includes a process chamber into which a substrate is transferred; a heating device heating the substrate, transferred into the process chamber, from its periphery side; a cooling device cooling the substrate, transferred into the process chamber, from its periphery side; a process gas supply unit supplying a process gas into the process chamber; and a control unit controlling the heating device and the cooling device to generate temperature difference between a center and the periphery sides of the substrate and controls the process gas supply unit. The control unit operates the process gas supply unit to stop operation of the cooling device during supply of the process gas into the process chamber.

TECHNICAL FIELD

The present disclosure relates to a substrate processing apparatus, asubstrate processing method, a semiconductor-device manufacturingmethod, and a control program.

BACKGROUND

For example, Patent Document 1 discloses a substrate processingapparatus which determines a temperature change amount for realizing adesired average temperature deviation, by using a deviation between atemperature of a substrate edge portion and a temperature of a substratecenter portion, which is generated when a heating temperature of asubstrate is changed in a predetermined time period, and a deviation ina steady state between the temperature of the substrate edge portion andthe temperature of the substrate center portion; controls a substrateheating temperature; and forms a film having uniform thickness on thesubstrate.

PRIOR ART DOCUMENT Patent Document

International Publication No. 2005/008755

Even if the desired average temperature deviation disclosed in PatentDocument 1 is realized, there is a limit in the thickness uniformity ofthe film formed on the substrate.

The present disclosure provides some embodiments of a substrateprocessing apparatus, a substrate processing method, a semiconductordevice manufacturing method, and a control program, which are capable ofcontrolling thickness uniformity of a film formed on a substrate.

SUMMARY

According to an aspect of the present disclosure, there is provided asubstrate processing apparatus, including a process chamber into which asubstrate is transferred; a heating device configured to heat thesubstrate, transferred into the process chamber, from a periphery sideof the substrate; a cooling device configured to cool the substrate,transferred into the process chamber, from the periphery side of thesubstrate; a process gas supply unit configured to supply a process gasinto the process chamber; and a control unit configured to control theheating device and the cooling device to generate a temperaturedifference between the center side and the periphery side of thesubstrate and controls the process gas supply unit, wherein the controlunit executes a first control, in which the heating device and thecooling device are operated, and a second control, in which operation ofat least the cooling device is stopped, after the first control; andoperates the process gas supply unit to supply the process gas into theprocess chamber at least during execution of the second control.

In addition, the control unit may operate the process gas supply unit tosupply the process gas into the process chamber for a specific timeperiod at least after the first control is switched to the secondcontrol.

Further, the control unit may operate the process gas supply unit tostart supplying the process gas into the process chamber when the firstcontrol is being executed.

Furthermore, the control unit may operate the process gas supply unit tosupply the process gas into the process chamber only during theexecution of the second control.

Additionally, the control unit may alternately and repeatedly executethe first control and the second control a predetermined number oftimes.

According to another aspect of the present disclosure, there is provideda substrate processing apparatus, including a process chamber into whicha substrate is transferred; a heating device configured to heat thesubstrate transferred into the process chamber from a periphery side ofthe substrate; a cooling device configured to cool the substratetransferred into the process chamber from the periphery side of thesubstrate; a process gas supply unit configured to supply a process gasinto the process chamber; and a control unit configured to control theheating device and the cooling device to generate a temperaturedifference between the center side and the periphery side of thesubstrate controls the process gas supply unit, wherein the control unitstops operation of the cooling device when the process gas supply unitis operated to supply the process gas into the process chamber.

According to still another aspect of the present disclosure, there isprovided a substrate processing method, including a first process inwhich a substrate is transferred into a process chamber; a secondprocess in which the substrate transferred into the process chamber iscooled from a periphery side of the substrate by a cooling device whilethe substrate is heated from the periphery side of the substrate by aheating device; a third process in which a process gas supply unit isoperated to start supplying a process gas into the process chamberduring execution of the second process; and a fourth process in whichoperation of the cooling device is stopped while the process gas issupplied in the third process after the second process ends.

According to yet another aspect of the present disclosure, there isprovided a substrate processing method, including a first process inwhich a substrate is transferred into a process chamber; a secondprocess in which the substrate transferred into the process chamber iscooled from a periphery side of the substrate by a cooling device whilethe substrate is heated from the periphery side of the substrate by aheating device; and a third process in which, after the second processends, operation of the cooling device is stopped and a process gassupply unit is operated to supply a process gas into the processchamber.

According to yet another aspect of the present disclosure, there isprovided a semiconductor device manufacturing method, including a firstprocess in which a substrate is transferred into a process chamber; asecond process in which the substrate transferred into the processchamber is cooled from a periphery side of the substrate by a coolingdevice while the substrate is heated from the periphery side of thesubstrate by a heating device; a third process in which a process gassupply unit is operated to start supplying a process gas into theprocess chamber during execution of the second process; and a fourthprocess in which operation of the cooling device is stopped while theprocess gas is supplied in the third process after the second processends.

Further, according to an aspect of the present disclosure, there isprovided a semiconductor device manufacturing method, including a firstprocess in which a substrate is transferred into a process chamber; asecond process in which the substrate transferred into the processchamber is cooled from a periphery side of the substrate by a coolingdevice while the substrate is heated from the periphery side of thesubstrate by a heating device; and a third process in which, after thesecond process ends, operation of the cooling device is stopped and aprocess gas supply unit is operated to supply a process gas into theprocess chamber.

According to another aspect of the present disclosure, there is provideda control program for causing a control unit to execute a first processin which a substrate is transferred into a process chamber; a secondprocess in which the substrate transferred into the process chamber iscooled from a periphery side of the substrate by a cooling device whilethe substrate is heated from the periphery side of the substrate by aheating device; a third process in which a process gas supply unit isoperated to start supplying a process gas into the process chamberduring execution of the second process; and a fourth process in whichoperation of the cooling device is stopped while the process gas issupplied after the second process ends.

In addition, according to an aspect of the present disclosure, there isprovided a control program for causing a control unit to execute a firstprocess in which a substrate is transferred into a process chamber; asecond process in which the substrate transferred into the processchamber is cooled from a periphery side of the substrate by a coolingdevice while the substrate is heated from the periphery side of thesubstrate by a heating device; and a third process in which, after thesecond process ends, operation of the cooling device is stopped and aprocess gas supply unit is operated to supply a process gas into theprocess chamber.

According to the present disclosure, it is possible to provide asubstrate processing apparatus, a substrate processing method, asemiconductor device manufacturing method, and a control program, whichare capable of controlling thickness uniformity of a film formed on asubstrate

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view illustrating an overall configuration of a substrateprocessing apparatus that is suitably used in a first embodiment of thepresent disclosure.

FIG. 2 is a view illustrating a process chamber which accommodates aboat and wafers illustrated in FIG. 1.

FIG. 3 is a view illustrating peripheral components of the processchamber illustrated in FIG. 1 and a configuration of a control unit (acontrol program) that controls the process chamber.

FIG. 4 is a view illustrating a configuration of the control unitillustrated in FIG. 1.

FIG. 5 is a view illustrating a shape of a wafer that is a processtarget of the substrate processing apparatus illustrated in FIG. 1.

FIG. 6 is a timing chart illustrating an example of a heating controland a process gas supply control of the substrate processing apparatusaccording to the first embodiment of the present disclosure.

FIG. 7 is a timing chart illustrating an example of a heating controland a process gas supply control of a substrate processing apparatusaccording to a second embodiment of the present disclosure.

FIG. 8 is a view illustrating heat transfer of an outer tube whenoperation of a cooling device is stopped.

FIG. 9 is a timing chart illustrating an example of a heating controland a process gas supply control of a substrate processing apparatusaccording to a third embodiment of the present disclosure.

FIG. 10 is a view illustrating a configuration of a substrate processingapparatus according to a fourth embodiment of the present disclosure.

FIG. 11 is a view illustrating a configuration of a substrate processingapparatus according to a fifth embodiment of the present disclosure.

FIG. 12 is a view illustrating an example of a calculation of pressuresetting values in the substrate processing apparatus according to thefifth embodiment of the present disclosure.

FIG. 13 is a view illustrating a temperature difference between a wafercenter side and a wafer periphery side when a pressure setting value ischanged in the substrate processing apparatus according to the fifthembodiment of the present disclosure.

FIG. 14 is a timing chart illustrating an example of a heating controland a process gas supply control of a substrate processing apparatusaccording to a sixth embodiment of the present disclosure.

DETAILED DESCRIPTION

Hereinafter, a substrate processing apparatus, a substrate processingmethod, a semiconductor device manufacturing method, and a controlprogram according to the present disclosure are described.

First Embodiment

A first embodiment of the present disclosure is described below.

[Substrate Processing Apparatus 1]

FIG. 1 is a view illustrating an overall configuration of a substrateprocessing apparatus 1 which is suitably used in a first embodiment ofthe present disclosure. FIG. 2 is a view illustrating a process chamber3 which accommodates a boat 14 and wafers (or substrates) 12 illustratedin FIG. 1. FIG. 3 is a view illustrating a peripheral configuration ofthe process chamber 3 that is illustrated in FIG. 1 and a configurationof a control program 40 that controls the substrate processing apparatus1.

A substrate processing apparatus 1 is a so-called reduced-pressure CVDapparatus that processes, for example, a wafer used in manufacturing asemiconductor device. As illustrated in FIG. 1, the substrate processingapparatus 1 includes a cassette delivery unit 100, a cassette stocker102 that is installed at a side of a rear surface of the cassettedelivery unit 100, a buffer cassette stocker 104 that is installed abovethe cassette stocker 102, a wafer transfer machine 106 that is installedat a side of a rear surface of the cassette stocker 102, a boat elevator108 that is installed at a side of a rear surface of the wafer transfermachine 106 and configured to convey the boat 14 on which the wafers 12are set, a process chamber 3 that is installed above the wafer transfermachine 106, and a control unit 2.

[Process chamber 3]

As illustrated in FIG. 2, the process chamber 3 includes a hollow heater32, an outer tube 360, an inner tube 362, a gas supply nozzle 340, a lidmember of a furnace port 344, an exhaust pipe 346, a rotation shaft 348,a manifold 350 made of, for example, stainless steel, O-rings 351, acooling gas flow path 352, an exhaust path 354, an exhaust unit 355, aheat insulator 300-1, and a heat insulator 300-2.

The heater 32 constitutes a heating device and heats the wafers 12,which have been transferred into the process chamber 3, from peripherysides (edge portions) of the wafers 12. The cooling gas flow path 352,the exhaust path 354, and the exhaust unit 355 constitute a coolingdevice and cool the wafers 12, which have been transferred into theprocess chamber 3, from the periphery sides (edge portions) of thewafers 12.

The outer tube 360 is made of a light-transmitting material, forexample, quartz, and is configured in a cylindrical shape with its lowerportion opened. The inner tube 362 is made of a light-transmittingmaterial, for example, quartz, and is configured in a cylindrical shapewith its upper and lower portions opened. The inner tube 362 is disposedin the outer tube 360 to be concentric with the outer tube 360. Acylindrical space is formed between the outer tube 360 and the innertube 362.

The heater 32 includes four temperature control parts 320-1 to 320-4that individually set and control temperatures. External temperaturesensors 322-1 to 322-4, such as thermocouples or the like, are disposedbetween the temperature control parts 320-1 to 320-4 and the outer tube300-1. The external temperature sensors 322-1 to 322-4 are installed atpositions corresponding to the temperature control parts 320-1 to 320-4and are configured to detect the temperatures of the temperature controlparts 320-1 to 320-4 or temperatures in the vicinity of the temperaturecontrol parts 320-1 to 320-4.

Internal temperature sensors 324-1 to 324-4, such as thermocouples orthe like, are disposed in the outer tube 360 (more specifically, in theinner tube 362). The internal temperature sensors 324-1 to 324-4 areinstalled at positions corresponding to the temperature control parts320-1 to 320-4 and are configured to detect temperature in the outertube 360 (more specifically, in the inner tube 362). The detectedtemperatures by the internal temperature sensors 324-1 to 324-4 are usedas values indicative of temperatures of the wafers 12 in heatingcontrol, which will be described later. Further, the internaltemperature sensors 324-1 to 324-4 may be installed between the innertube 362 and the outer tube 360. In addition, the internal temperaturesensors 324-1 to 324-4 may be bent toward an inner side of the innertube 362, at positions corresponding to the temperature control parts320-1 to 320-4, so as to detect temperatures at spaces between thewafers 12 (e.g., a temperature at a region above a center portion of thewafer 12).

Each of the temperature control parts 320-1 to 320-4 of the heater 32is, for example, an optical heating device and is configured to emitlight for optically heating the wafers 12 from a periphery of the outertube 360. The light emitted from the temperature control parts 320-1 to320-4 is transmitted through the outer tube 360 and the inner tube 362and is absorbed by the wafers 12 held in the boat 14. Thus, the wafers12 are heated from their peripheral sides. Reference numeral 140indicates a heat insulating plate disposed below the boat 14. The heatinsulating plate 140 suppresses heat transfer down the boat 14.

The cooling gas flow path 352 is formed between the heat insulator 300-1and the outer tube 360 so as to allow fluid such as a cooling gas or thelike to pass between the heat insulator 300-1 and the outer tube 360.The cooling gas is supplied from an intake hole 353 formed in a lowerend portion of the heat insulator 300-1 and is allowed to flow toward anupper side of the outer tube 360 through the cooling gas flow path 352.The cooling gas may be, for example, air or nitrogen (N₂) gas.

Further, the cooling gas flow path 352 is configured such that thecooling gas is injected toward the outer tube 360 from between thetemperature control parts 320-1 to 320-4. The cooling gas cools theouter tube 360. The cooled outer tube 360 then cools the wafers 12,which are held in the boat 14, from the periphery sides of the wafers12. As such, the wafers 12 are cooled from their periphery sides by thecooling gas that passes through the cooling gas flow path 352.

An exhaust path 354 is installed at an upper side of the cooling gasflow path 352 to be used as a cooling gas exhaust path. The exhaust path354 guides the cooling gas, which has been supplied from the intake hole353 and flows upward through the cooling gas flow path 352, outside ofthe heat insulator 300-2.

The exhaust unit 355 is installed in the exhaust path 354. The exhaustunit 355 includes a cooling gas exhaust device 356, implemented with ablower or the like, and a radiator 357. The cooling gas is sucked up bythe cooling gas exhaust device 356 and is discharged from an exhausthole 358 installed at a downstream side of the cooling gas exhaustdevice 356. The radiator 357 cools, with cooling water or the like, thecooling gas that has been heated as it cools the outer tube 360 and thewafers 12 in the process chamber 3. Shutters 359 are installed in thevicinity of the intake hole 353 and the radiator 357, and are controlledby a shutter control unit (not illustrated) so as to open or close thecooling gas flow path 352 and the exhaust path 354.

As illustrated in FIG. 3, the substrate processing apparatus 1 furtherincludes a temperature control device 370, a temperature measurementdevice 372, a process gas flow rate control device (a process gas supplyunit or a mass flow controller (MFC)) 374, a boat elevator controldevice (an elevator controller (EC)) 376, a pressure sensor (PS) 378, apressure regulating device (or an automatic pressure controller (valve)(APC)) 380, a process gas exhaust device (EP) 382, and an inverter 384.

Under the control of the control unit 2, the temperature control device370 drives each of the temperature control parts 320-1 to 320-4. Thetemperature measurement device 372 detects the temperature of each ofthe temperature sensors 322-1 to 322-4 and 324-1 to 324-4, and outputsthe detected temperature as a temperature measurement value to thecontrol unit 2.

Under the control of the control unit 2, the boat elevator controldevice (EC) 376 drives the boat elevator 108. For example, an APC or aN₂ ballast controller is used as the pressure regulating device(hereinafter, referred to as an APC) 380. For example, a vacuum pump isused as the EP 382. The inverter 384 controls an operation speed of thecooling gas exhaust device 356 (the revolution-number of a blower).

[Control Unit 2]

FIG. 4 is a view illustrating a configuration of the control unit 2illustrated in FIG. 1. As illustrated in FIG. 4, the control unit 2includes a CPU 200, a memory 204, a display/input unit 22 including adisplay device, a touch panel, a keyboard, a mouse, etc., and arecording unit 24 such as a HD, a CD, or the like. As such, the controlunit 2 includes components as a general computer capable of controllingthe substrate processing apparatus 1. Using the components, the controlunit 2 executes a control program for a reduced-pressure CVD process(e.g., a control program 40, as illustrated in FIG. 3, including acontrol of heating or a control of the process gas supply unit, whichwill be described later) so that each of the components in the substrateprocessing apparatus 1 is controlled to perform the reduced-pressure CVDprocess, which will be described later.

[Control Program 40]

Reference is made to FIG. 3 again. As illustrated in FIG. 3, the controlprogram 40 includes a process control unit 400, a temperature controlunit 410, a process gas flow rate control unit 412, a drive control unit414, a pressure control unit 416, a process gas exhaust device controlunit 418, a temperature measurement unit 420, a cooling gas flow ratecontrol unit 422, and a temperature setting value storage unit 424. Thecontrol program 40 is supplied to the control unit 2, for example, via arecording medium 240 (see FIG. 4). The control program 40 is loaded ontothe memory 204 and is executed.

The temperature setting value storage unit 424 stores temperaturesetting values in a process recipe for the wafers 12 and outputs thetemperature setting values to the process control unit 400. The processcontrol unit 400 controls each component in the control program 40, inresponse to a user's manipulation to the display/input unit 22 (see FIG.4) of the control unit 2 or pursuant to a process sequence (or theprocess recipe) recorded in the recording unit 24, so as to perform thereduced-pressure CVD process for the wafers 12, which will be describedlater.

The temperature measurement unit 420 receives temperature measurementvalues of the temperature sensors 322 and 324 via the temperaturemeasurement device 372 and outputs the temperature measurement values tothe process control unit 400. The temperature control unit 410 controlsthe heating device based on the temperatures detected by the temperaturesensors 322 and 324. Specifically, the temperature control unit 410receives the temperature setting values and the detected temperatures bythe temperature sensors 322-1 to 322-4 and 324-1 to 324-4 from theprocess control unit 400, and feedback-controls electric power suppliedto the temperature control parts 320-1 to 320-4 based on the temperaturesetting values and the detected temperatures so that an interior of theouter tube 360 is heated for the wafers 12 to reach a desiredtemperature.

The process gas flow rate control unit 412 controls the MFC 374 andadjusts a flow rate of a process gas or an inert gas supplied into theouter tube 360. The drive control unit 414 controls the boat elevator108 to move up or down the boat 14 and the wafers 12 held in the boat14. Furthermore, the drive control unit 414 controls the boat elevator108 to rotate, via the rotation shaft 348, the boat 14 and the wafers 12held in the boat 14.

The pressure control unit 416 controls the APC 380, based on a pressureof the process gas in the outer tube 360 detected by the PS 378, toallow the process gas in the outer tube 360 to have a desired pressure.The process gas exhaust device control unit 418 controls the EP 382 toexhaust the process gas or the inert gas existing in the outer tube 360.

The cooling gas flow rate control unit 422 controls operation of thecooling device. Specifically, the cooling gas flow rate control unit 422controls operation of the cooling gas exhaust device 356 via theinverter 384 so that the flow rate of the cooling gas becomes equal to apredetermined flow rate to allow the wafers 12 to have a desiredtemperature. Further, the cooling gas flow rate control unit 422 mayreceive the temperature setting values and the detected temperatures bythe temperature sensors 322-1 to 322-4 and 324-1 to 324-4 from theprocess control unit 400, and may control operation of the cooling gasexhaust device 356 based on the temperature setting values and thedetected temperatures.

When it is not necessary to specifically indicate one of the componentssuch as the temperature control parts 320-1 to 320-4 or the like in thefollowing descriptions, the temperature control parts 320-1 to 320-4 maybe simply abbreviated as a temperature control part 320. Additionally,although the number of the components such as the temperature controlparts 320-1 to 320-4 or the like may be specified in the followingdescriptions, the number of the components is illustrated for the sakeof concrete and clear description and is not intended to limit thetechnical scope of the present disclosure.

The O-rings 351 are disposed between a lower end of the outer tube 360and an upper opening portion of the manifold 350 and between the lidmember of a furnace port 344 and a lower opening portion of the manifold350 so as to hermetically seal a gap between the outer tube 360 and themanifold 350. An inert gas or a process gas is supplied into the innertube 362 through the gas supply nozzle 340 positioned below the outertube 360.

The exhaust pipe 346 (see FIG. 2) connected to the PS 378, the APC 380,and the EP 382 is installed above the manifold 350. The process gassupplied into the inner tube 362 passes through an interior of the innertube 362 and then passes through between the outer tube 360 and theinner tube 362. The process gas is discharged out of the process chamber3 via the exhaust pipe 346, the APC 380, and the EP 382.

When it is required to supply an inert gas to allow an interior of theouter tube 360 to be at a normal pressure, the APC 380 adjusts aninternal pressure of the outer tube 360 pursuant to an instruction ofthe pressure control unit 416 such that the interior of the outer tube360 is controlled to be at the normal pressure. Alternatively, when itis required to supply a process gas to process the wafers 12, the APC380 adjusts the internal pressure of the outer tube 360 pursuant to aninstruction of the pressure control unit 416 so that the interior of theouter tube 360 is controlled to be of a desired low pressure.

The rotation shaft 348 is connected to a lower portion of the boat 14that holds the plurality of wafers 12. The rotation shaft 348 isconnected to the boat elevator 108 (see FIG. 1). Under the control ofthe EC 376, the boat elevator 108 moves the boat 14 up or down at acertain speed and rotates the wafers 12 and the boat 14 at a certainspeed via the rotation shaft 348.

The wafers 12 used as workpieces are accommodated in a wafer cassette490 (see FIG. 1). In this state, the wafers 12 are conveyed from theoutside of the substrate processing apparatus 1 and are mounted on thecassette delivery unit 100. The cassette delivery unit 100 transfers thewafers 12 to the cassette stocker 102 or the buffer cassette stocker104. The wafer transfer machine 106 takes out the wafers 12 from thecassette stocker 102 and loads the wafers 12 onto the boat 14 in ahorizontal posture and in multiple stages.

The boat elevator 108 moves up the boat 14 with the wafers 12 loaded andtransfers the boat 14 into the process chamber 3. In addition, the boatelevator 108 moves down the boat 14 with the processed wafers 12 loadedand takes the boat 14 out of an interior of the process chamber 3. Theprocessed wafers 12 are returned from the boat 14 to the cassettestocker 102 by the wafer transfer machine 106 and are then transferredout of the substrate processing apparatus 1 via the cassette deliveryunit 100.

[Temperature of Wafers 12 and Film Thickness]

FIG. 5 is a view illustrating a shape of the wafer 12 to be processed inthe substrate processing apparatus 1. A surface of the wafer 12(hereinafter, which may sometimes be simply referred to as the wafer 12)has a substantially circular shape as illustrated in FIG. 5 and ishorizontally held in the boat 14.

As described above, the wafer 12 is heated from a periphery of the outertube 360 by the temperature control parts 320-1 to 320-4. Accordingly, aperiphery side of the wafer 12 absorbs a large amount of light. When thecooling gas does not flow through the cooling gas flow path 352, atemperature of the periphery side (edge portion) of the wafer 12 becomeshigher than a temperature of a center side (center portion) of the wafer12. As such, as the wafer 12 is heated by the temperature control parts320-1 to 320-4, a temperature of the wafer 12 increases from the centerportion to the edge portion so as to cause a cone-shaped temperaturedistribution whose bottom is at the center portion of the wafer 12.

In addition, the process gas such as a reaction gas or the like issupplied from the periphery side of the wafer 12. Therefore, dependingon the kind of a film formed on the wafer 12, a reaction speed in theedge portion of the wafer 12 may differ from a reaction speed in thecenter portion of the wafer 12. For example, the process gas is consumedat the periphery side of the wafer 12 and then flows to the center sideof the wafer 12. Thus, a concentration of the process gas at the centerside of the wafer 12 is lower than the concentration of the process gasat the periphery side of the wafer 12. Therefore, even if the abovetemperature distribution is not caused in the surface of the wafer 12, athickness of a film formed on the wafer 12 may become non-uniform sincethe process gas is supplied from the periphery side of the wafer 12.

On the other hand, if the cooling gas is allowed to pass through thecooling gas flow path 352, the wafer 12 is cooled from its peripheryside as described above. As such, the substrate processing apparatus 1causes the temperature control part 320 to heat the center side of thewafer 12 to a specified set temperature (a process temperature) andallows the cooling gas to pass through the cooling gas flow path 352 asneeded. As a result, different temperatures can be set at the centerside and the periphery side of the wafer 12. Therefore, thicknessuniformity of a film formed on a substrate can be controlled.

As described above, in the substrate processing apparatus 1, the heatingcontrol (the control including heating and cooling) for controlling filmthickness is performed depending on a film-forming reaction speed. Thecontrol unit 2 controls the heater 32 and the cooling gas exhaust device356 to perform the heating control.

[Overview of Reduced-Pressure CVD Process Using Substrate ProcessingApparatus 1]

Under the control of the control program 40 (see FIG. 3) executed on thecontrol unit 2 (see FIGS. 1 and 4), the substrate processing apparatus 1employs CVD to form a Si₃N₄ film, a SiO₂ film, a polysilicon (Poly-Si)film, or the like on the wafers 12 transferred into the process chamber3.

The film formation using the process chamber 3 is described again.First, the boat elevator 108 moves the boat 14 down. A desired number ofwafers 12 as process targets are set in the lowered boat 14. The boatelevator 108 moves the boat 14, in which the wafers 12 are set, into theouter tube 360 (into the inner tube 362). As such, the wafers 12 aretransferred into the process chamber 3.

Then, each of four temperature control parts 320-1 to 320-4 of theheater 32 heats the interior of the outer tube 360 under the control ofthe control unit 2 so that the temperature of the center sides (thecenter portions) of the wafers 12 reach a predetermined temperature (aprocess temperature). Additionally, the control unit 2 controls thecooling gas exhaust device 356 to allow the cooling gas to flow throughthe cooling gas flow path 352. Thus, the wafers 12 are cooled from theirperiphery sides.

Then, the interior of the outer tube 360 is vacuum-exhausted by the EP382 to allow the interior of the outer tube 360 to have a desiredpressure (vacuum degree). Subsequently, the boat 14 and the wafers 12held in the boat 14 are rotated via the rotation shaft 348. If theprocess gas is supplied into the outer tube 360 through the gas supplynozzle 340 in the above state, the process gas supplied as above ismoved upward in the inner tube 362 and is uniformly supplied to therespective wafers 12.

The EP 382 exhausts the process gas through the exhaust pipe 346 fromthe interior of the process chamber 3 which is performing thereduced-pressure CVD process. The APC 380 maintains the process gas inthe outer tube 360 to be of a desired pressure. In this manner, thereduced-pressure CVD process is performed on the wafers 12 for aspecified period of time.

If the reduced-pressure CVD process is completed, the process gas in theouter tube 360 is replaced with an inert gas and the internal pressureof the outer tube 360 is regulated to a normal pressure so as to proceedto the process for next wafers 12. In addition, the cooling gas isallowed to flow through the cooling gas flow path 352 so that theinterior of the outer tube 360 is cooled to a specific temperature. Inthis state, the boat 14 and the processed wafers 12 held in the boat 14are moved down by the boat elevator 108 and are unloaded of the processchamber 3.

Further, in some embodiments, the cooling gas is allowed to flow evenwhen the boat 14 is moved into the process chamber 3 and even when theboat 14 is unloaded of the process chamber 3. As a result, the processchamber 3 can be prevented from being filled with heat due to a heatcapacity of the process chamber 3 and a temperature of the processchamber 3 can be prevented from fluctuating. Throughput can also beimproved.

In the film forming process as described above, if the heating controlis performed by the cooling gas so that a temperature difference isgenerated between the temperature of the periphery side and thetemperature of the center side of the wafer 12 while the heater 32 iscontrolled to maintain the temperature of the center side of the wafer12 at a preset temperature, in-plane film thickness uniformity of thewafer 12 and inter-plane film thickness uniformity can be improvedwithout changing film quality. For example, in the case of forming a CVDfilm such as a Si₃N₄ film or the like, if a film-forming process isperformed while a process temperature changes in a wide range, arefractive index of the film may change depending on the processtemperature. If the film-forming process is performed while the processtemperature is lowered from a high temperature to a low temperature, thefilm may change from a film having a low etching rate to a film having ahigh etching rate depending on the process temperature. Further, in thecase of forming the Si₃N₄ film, if the film-forming process is performedwhile the process temperature is lowered from a high temperature to alow temperature, the film may change from a film having a high stressvalue to a film having a low stress value depending on the processtemperature.

Accordingly, the substrate processing apparatus 1 controls an in-planetemperature distribution of the wafer 12 by controlling an amount ofheat that is generated by the temperature control part 320 and a flowrate of the cooling gas that passes through the cooling gas flow path352. As a result, the thickness uniformity of the film formed on thewafer 12 can be controlled without changing film quality.

Subsequently, a heating control and a process gas supply control aredescribed below in detail. The control unit performs the heating controland the process gas supply control.

FIG. 6 is a timing chart illustrating an example of the heating controland the process gas supply control for the substrate processingapparatus 1 according to the first embodiment of the present disclosure.As illustrated in FIG. 6, the control unit 2 first controls operation ofthe heating device (specifically, the temperature control part 320 inthe heater 32) such that a temperature detected by the internaltemperature sensor 324 is increased from a specific standby temperatureto a specific process temperature (a preset temperature). Thus, atemperature of the center side of the wafer 12 is increased to theprocess temperature. In addition, although the detected temperature bythe internal temperature sensor 324 and the temperature of the centerside of the wafer 12 may not be strictly identical to each other, acorrelation between the detected temperature by the internal temperaturesensor 324 and the temperature of the center side of the wafer 12, whenthe amount of the heat generated by the temperature control part 320 andthe flow rate of the cooling gas are set to be proper values, may befound in advance, and the temperature of the center side of the wafer 12may be controlled to be a specific temperature based on the detectedtemperature by the internal temperature sensor 324. For ease ofunderstanding, the detected temperature by the internal temperaturesensor 324 is regarded as the temperature of the center side of thewafer 12 in the following descriptions.

If the temperature detected by the internal temperature sensor 324reaches the process temperature (if the temperature of the center sideof the wafer 12 reaches the process temperature), the control unit 2starts operation of the cooling device (specifically, the control unit 2operates the cooling gas exhaust device 356 to allow the cooling gas toflow through the cooling gas flow path 352 at a predetermined flowrate). If the operation of the cooling device is started, the wafer 12is cooled from its periphery side. The temperature of the center side ofthe wafer 12 is maintained at the process temperature by controlling theheating device such that the temperature detected by the internaltemperature sensor 324 becomes equal to the process temperature. Here,by the cooling gas flowing through the cooling gas flow path 352, thetemperature of the periphery side of the wafer 12 is maintained at aspecific temperature lower than the temperature of the center side ofthe wafer 12.

If the temperature detected by the internal temperature sensor 324 isstabilized at the process temperature (if the temperature of the centerside and the temperature of the periphery side of the wafer 12 arestabilized at preset temperatures, respectively, and, specifically, ifthe temperature of the center side is stabilized with a specifictemperature difference from the temperature of the periphery side of thewafer 12), the control unit 2 operates the process gas flow rate controldevice (MFC) 374 and starts the supply of the process gas into theprocess chamber 3 (the interior of the outer tube 360). The time takenfrom the start of the operation of the cooling device to the start ofthe supply of the process gas (the period indicated as “STABLE” in FIG.6) may be determined in advance, for example, based on experiments.

In the lower portion of FIG. 6, there is illustrated a change in thetemperature difference between the center side and the periphery side ofthe wafer 12 (a change in the value obtained by subtracting thetemperature of the center side from the temperature of the peripheryside of the wafer 12). As illustrated, during a process period (a supplyperiod of the process gas, which is the period indicated as “DEPOSITION”in FIG. 6), the temperature of the periphery side of the wafer 12 ismaintained to be lower than the temperature of the center side by aspecific temperature.

As described above, if the process gas is supplied from the peripheryside of the wafer, the process gas is consumed at the periphery side ofthe wafer and then flows to the center side of the wafer. Thus, theconcentration of the process gas at the center side of the wafer may belower than the concentration of the process gas at the periphery side ofthe wafer. In this case, a film thickness at the center side of thewafer may become smaller than a film thickness at the periphery side ofthe wafer. In contrast, according to the first embodiment of the presentdisclosure, during the supply period of the process gas, the controlunit 2 controls the heating device and the cooling device to maintainthe temperature of the periphery side of the wafer to be lower than thetemperature of the center side of the wafer by a specific temperaturedifference. As a result, film formation at the periphery side of thewafer is suppressed. It is, therefore, possible to make the thickness ofthe film formed on the wafer uniform.

Second Embodiment

Next, a second embodiment of the present disclosure is described below.

In the first embodiment as described above, during the supply period ofthe process gas, the temperature of the periphery side of the wafer ismaintained to be lower than the temperature of the center side of thewafer by a specific temperature difference so as to make the thicknessof the film formed on the wafer uniform. In this case, if it is intendedto increase the temperature difference between the periphery side andthe center side of the wafer (if it is intended to decrease thetemperature of the periphery side of the wafer to be lower than thetemperature of the center side of the wafer), it may be considered toimprove a cooling performance of the cooling device. However, if thecooling performance of the cooling device is enhanced, the load of theheating device for maintaining the temperature of the center side of thewafer constant is increased. Thus, according to the second embodiment ofthe present disclosure, the heating control and the process gas supplycontrol are improved such that a large temperature difference can begenerated between the center side and the periphery side of the waferwithout enhancing the cooling performance of the cooling device.

FIG. 7 is a timing chart illustrating an example of a heating controland a process gas supply control for the substrate processing apparatus1 according to the second embodiment of the present disclosure. Sincethe configuration of the substrate processing apparatus 1 according tothe second embodiment is the same as the configuration of the substrateprocessing apparatus 1 according to the first embodiment, thedescriptions for the substrate processing apparatus 1 are omitted.

As illustrated in FIG. 7, the control unit 2 first controls operation ofthe temperature control part 320 of the heating device (the heater 32)so that the temperature detected by the internal temperature sensor 324is increased from a standby temperature to a process temperature. As aresult, the temperature of the center side of the wafer 12 is increasedto the process temperature. If the temperature detected by the internaltemperature sensor 324 reaches the process temperature (if thetemperature of the center side of the wafer 12 reaches a settemperature), the control unit 2 starts operation of the cooling device.The above procedures are the same as those described with reference tothe first embodiment.

In the second embodiment of the present disclosure, if the temperaturedetected by the internal temperature sensor 324 is stabilized at theprocess temperature (if the temperature of the center side of the wafer12 is stabilized at the process temperature), the control unit 2 stopsoperating the cooling device and operates the process gas flow ratecontrol device 374 so that the supply of the process gas into theprocess chamber 3 (the interior of the outer tube 360) is started.

As illustrated in the lower portion of FIG. 7, the temperaturedifference between the center side and the periphery side of the wafer12 remains large over a certain time period after the operation of thecooling device is stopped. This means that the temperature of theperiphery side of the wafer 12 is largely decreased when compared to thetemperature of the center side of the wafer 12. As such, if theoperation of the cooling device is stopped from the operating state, thetemperature of the periphery side of the wafer is temporarily decreasedfaster than the temperature of the center side of the wafer. The reasonis as follows. First, if the operation of the cooling device is stopped,the temperature of the interior of the process chamber 3 (the interiorof the outer tube 360) is going to rise. Then, the heating device iscontrolled to stop its operation or reduce its output (a heat generationamount). As illustrated in FIG. 8, if the heat generation amount of theheating device is reduced, heat transfer from the outer tube 360 to itsoutside is increased and a heat radiation amount from the periphery sideof the wafer 12 is increased. Therefore, after the cooling device isstopped, the temperature of the periphery side of the wafer istemporarily decreased faster than the temperature of the center side ofthe wafer.

Accordingly, in the second embodiment, the control unit 2 stops theoperation of the cooling device when the supply of the process gas intothe process chamber 3 is started by operating the process gas flow ratecontrol device 374. As a result, the temperature of the periphery sideof the wafer 12 can be lowered more drastically than the temperature ofthe center side of the wafer 12 without having to enhance the coolingperformance of the cooling device. Thus, a larger temperature differencecan be caused between the center side and the periphery side of thewafer 12. Accordingly, thickness uniformity of a film formed on thewafer can be controlled efficiently and to the film thickness uniformitycan be further improved.

Reference is made to FIG. 7 again. In the following descriptions, thecontrol of operating both the heating device and the cooling device (thecontrol of both heating the wafer from its periphery side by using theheating device and cooling the wafer by using the cooling device) willbe referred to as “first control.” The control of stopping operation ofat least the cooling device after the first control will be referred toas “second control.”

[Start Timing of Second Control]

As can be noted from a comparison of FIGS. 6 and 7, in the firstembodiment as described above, the supply of the process gas is startedafter the temperature of the periphery side of the wafer 12 is decreasedto be lower than the temperature of the center side of the wafer 12 by aspecific temperature. In the second embodiment, the second control isstarted and the supply of the process gas is started before thetemperature of the periphery side of the wafer 12 decreases to be lowerthan the temperature of the center side of the wafer 12. This is becausein the second embodiment, the temperature of the periphery side of thewafer 12 can be effectively reduced by executing the second control.

As such, in the second embodiment, an execution time period of the firstcontrol is set to be a predetermined time period (a time period in whichthe temperature difference between the center side and periphery side ofthe wafer 12 reaches a specific temperature by the first control whilethe temperature of the center side of the wafer 12 is maintained at aspecific temperature). After the first control is executed for the timeperiod, the second control is started.

Further, in the second embodiment, the second control is started beforethe temperature of the periphery side of the wafer 12 decreases to belower than the temperature of the center side of the wafer 12. Thus, inthe second embodiment, a cooling device, whose cooling performance islower than that of the cooling device used in the first embodiment, maybe employed. In addition, in the second embodiment, the cooling deviceis not operated continuously for a long period of time. Thus, the loadof the heating device due to the cooling is reduced. Accordingly,contrary to the above descriptions, the cooling performance of thecooling device can be improved and the periphery side of the wafer 12can be cooled in a short period of time. As a result, the execution timeperiod of the first control can be shortened. Moreover, the secondcontrol may be executed after the temperature of the periphery side ofthe wafer 12 decreases to be lower than the temperature of the centerside of the wafer 12. Similar to the first embodiment, the secondcontrol may be executed after the temperature difference between thetemperature of the periphery side of the wafer 12 and the temperature ofthe center side of the wafer 12 is stabilized.

[Execution Time Period of Second Control]

As illustrated in FIG. 7, the second control is executed for a specificperiod of time after the first control. During the execution of thesecond control, the process gas flow rate control device 374 is operatedto supply the process gas to the process chamber 3.

The execution time period of the second control is determined in advancebased on experiments or the like. Although operation of the coolingdevice is stopped, temperature in the outer tube 360 decreases due tonatural heat dissipation. Thus, the control unit 2 controls the heatingdevice so that the temperature detected by the internal temperaturesensor 324 is maintained to be the process temperature. As describedabove, the heating device heats the wafer 12 from its periphery side.Therefore, while the cooling device is stopped, the temperature of thewafer 12 is more easily increased at its periphery side than at itscenter side. Accordingly, when the time period, in which the temperatureof the periphery side of the wafer decreases faster than the temperatureof the center side of the wafer, is elapsed after the cooling device isstopped, the temperature difference between the center side and theperiphery side becomes smaller. Eventually, the temperature of theperiphery side exceeds the temperature of the center side. Thus, thetime period, in which a difference equal to or larger than a specifictemperature can be generated between the center side and the peripheryside of the wafer 12, namely, the time period, in which the temperatureof the periphery side can be maintained to be lower than the temperatureof the center side by a specific temperature or more, is measured inadvance by experiments or the like. The time period as measured above isset as the execution time period of the second control.

If a desired thickness for a film cannot be formed during the executiontime period of the second control, that is, if the execution time periodof the second control fails to meet a specific process time period, thesupply of the process gas is stopped and the cooling device is operatedagain to execute to the first control. Thereafter, the operation of thecooling device is stopped again to execute the second control and thesupply of the process gas is performed. In this manner, a specificprocess time period can be secured by alternately and repeatedlyexecuting the first control and the second control a predeterminednumber of times.

In FIG. 7, a start timing of the second control (a timing at which theoperation of the cooling device is stopped) and a start timing of thesupply of the process gas are brought into coincidence with each other.An end timing of the second control 7 (a timing at which the operationof the cooling device is resumed) and an end timing of the supply of theprocess gas are brought into coincidence with each other. However, theprocess gas needs to be supplied at least for a certain period of timewhile the second control is performed. Accordingly, for example, thestart timing of the supply of the process gas may be set to be laterthan the start timing of the second control. Furthermore, the end timingof the supply of the process gas may be set to be earlier than the endtiming of the second control. As such, if the process gas is suppliedfor a specified time period while the second control is executed atleast after the first control is switched to the second control,efficient cooling effect for the periphery side of the wafer by usingthe second control can be achieved. However, to secure a process timeperiod, the execution time period of the second control and the supplytime of the process gas can be brought into coincidence with each other.

Third Embodiment

Next, a third embodiment of the present disclosure is described below.

FIG. 9 is a timing chart illustrating an example of a heating controland a process gas supply control for the substrate processing apparatus1 according to a third embodiment of the present disclosure. Since theconfiguration of the substrate processing apparatus 1 according to thethird embodiment is the same as the configuration of the substrateprocessing apparatus 1 according to the first embodiment, thedescriptions for the substrate processing apparatus 1 are omitted.

In the third embodiment, as shown in FIG. 9, the second control isexecuted after the temperature of the periphery side of the wafer 12becomes lower than the temperature of the center side by a specifictemperature over the first control while the temperature of the centerside of the wafer 12 is maintained at a specific temperature. While thefirst control is executed (specifically, when the temperature of theperiphery side of the wafer 12 is stabilized at a temperature that islower than the temperature of the center side by a specific temperaturewhile the temperature of the center side of the wafer 12 is maintainedat a specific temperature), the process gas flow rate control device 374is operated so as to start the supply of the process gas into theprocess chamber 3. As such, in the third embodiment, after the firstcontrol is executed, operation of the cooling device is stopped whilethe process gas is supplied. In other words, the operation of thecooling device is stopped only for a specified time period in the waferprocess time period (the time period of the supply of the process gas).

As illustrated in FIG. 9, the control unit 2 first controls operation ofthe heating device (the temperature control part 320 of the heater 32)so that the temperature detected by the internal temperature sensor 324is increased from a standby temperature to a process temperature. As aresult, the temperature of the center side of the wafer 12 is increasedto the process temperature. If the temperature detected by the internaltemperature sensor 324 reaches the process temperature (if thetemperature of the center side of the wafer 12 reaches the processtemperature), the control unit 2 starts the operation of the coolingdevice (starts the first control). The procedures described above arethe same as the procedures of the aforementioned embodiments.

If a predetermined time period (specifically, a time period in which thetemperature of the periphery side of the wafer 12 is stabilized at atemperature that is lower than the temperature of the center side by aspecific temperature while the temperature of the center side of thewafer 12 is maintained at the process temperature) is elapsed, theprocess gas flow rate control device 374 is operated to start the supplyof the process gas into the process chamber 3 (the interior of the outertube 360).

Subsequently, when the process gas has been supplied for a specifiedtime period, the control unit 2 stops the operation of the coolingdevice (starts the second control) while the process gas is suppliedcontinuously. As illustrated in the lower portion of FIG. 9, althoughthe temperature of the periphery side of the wafer 12 had beenmaintained to be lower than the temperature of the center side by aspecific temperature, if the operation of the cooling device is stopped,the temperature of the periphery side of the wafer 12 is decreased moresharply than the temperature of the center side for a specified time asdescribed above with reference to the second embodiment. As a result,the temperature of the periphery side of the wafer 12 can be decreasedmore sharply than the temperature of the center side without having toenhance the cooling performance of the cooling device. Thus, a largertemperature difference can be caused between the center side and theperiphery side of the wafer 12. Accordingly, thickness uniformity of thefilm formed on the wafer can be controlled effectively and the filmthickness uniformity can be improved.

[Start Timing of Second Control]

The start timing of the second control in the third embodiment isdetermined, for example, in the following manner.

(1) The case where the first control and the second control are executedfor only one cycle

If executing the first control and the second control for one cyclesatisfies a desired process time period, the second control is startedat a timing which precedes an end timing of the desired process timeperiod by a time period in which the cooling effect for the peripheryportion of the wafer can be obtained through the second control ([theexecution time period of the second control] described above withreference to the second embodiment). The supply of the process gas iscontinuously performed until the second control comes to an end.

(2) The case where the first control and the second control are executeda plurality of cycles

The second control is started at a timing which precedes an end timingof the process time period for one cycle by a time period in which thecooling effect for the periphery portion of the wafer can be obtainedthrough the second control ([the execution time period of the secondcontrol] described above with reference to the second embodiment). Afterthe second control is completed, the operation of the cooling device isresumed to execute the first control. The supply of the process gas iscontinuously performed until the second control comes to an end and iscompleted simultaneously with the end of the second control. If apredetermined time period (specifically, a time period in which thetemperature of the periphery side of the wafer 12 is stabilized at atemperature lower than the temperature of the center side by a specifictemperature while the temperature of the center side of the wafer 12 ismaintained at a specific temperature) elapses after the first control isresumed, the supply of the process gas is started again. Thereafter, thesame procedures are performed a predetermined number of cycles.

In each of cases (1) and (2) as described above, the supply of theprocess gas may be ended within the second control. Additionally, thesupply of the process gas may be continuously performed when the secondcontrol is switched to the first control.

In the third embodiment, thickness uniformity of the film formed on thewafer can be effectively controlled while the wafer process conditionsof the first embodiment are used. Thus, the film thickness uniformitycan be further improved. Similar to the second embodiment, the processtime period per one cycle is not limited to the execution time period ofthe second control. Therefore, the process time period for one cycle canbe set to be an optimal time period which realizes a desired processtime period.

Fourth Embodiment

Next, a fourth embodiment of the present disclosure is described below.

[Exhaust Pressure and Film Thickness]

As described above, when a film is formed on the wafer 12 in thesubstrate processing apparatus 1, the heating control is executed by atleast one of the control, in which the control unit 2 controls thetemperature control part 320 of the heater 32 based on a measurementvalue of the internal temperature sensor 324, and the control, in whichthe control unit 2 controls the cooling gas exhaust device 356 by usingthe cooling gas flow rate control unit 422 and the inverter 384. When acooling gas is allowed to flow through the cooling gas flow path 352,the cooling gas moves through the cooling gas flow path 352 and theexhaust path 354 to be exhausted from the exhaust hole 358 by theexhaust unit 355. The exhaust hole 358 is connected to an exhaustfacility of a factory or the like, not illustrated in the drawings.

An exhaust pressure of the exhaust facility is affected by conductanceattributable to a length of a pipe between the exhaust facility and theexhaust hole 358, a shape of the pipe, a route of the piping route, andthe like, or affected by the number of the devices connected to theexhaust facility and the like. Thus, exhaust pressures of all theexhaust facilities are different from each other and the exhaustpressure may vary even in the same exhaust facility. If the facilitypressure of the exhaust facility changes, an amount of the gas flowingthrough the cooling gas flow path 352 changes even though the coolinggas exhaust device 356 is controlled with a constant control value. Forexample, if it is assumed that the facility exhaust pressure decreasesfrom 200 Pa to 150 Pa, a flow rate of the cooling gas flowing throughthe cooling gas flow path 352 decreases. On the other hand, if it isassumed that the facility exhaust pressure increases from 150 Pa to 200Pa, the flow rate of the cooling gas flowing through the cooling gasflow path 352 increases.

If a cooling performance varies with the change in the exhaust pressureof the exhaust facility as described above, variation of the coolingperformance may affect thickness uniformity of a film formed on thewafer 12.

Accordingly, in the fourth embodiment, an attempt is made to ensure thata thickness of a film formed on the wafer 12 can be made uniform even ifthere is a variation or a change in the exhaust pressure of thefacility.

FIG. 10 is a view illustrating a configuration of a substrate processingapparatus according to the fourth embodiment of the present disclosure.The substrate processing apparatus according to the fourth embodiment ofthe present disclosure includes not only the components of the substrateprocessing apparatus 1 in the first embodiment but also its owncomponents for making the film thickness of the wafer 12 uniform even ifthere is a variation or a change in the exhaust pressure of thefacility. Some of the components identical with those of the substrateprocessing apparatus 1 in the first embodiment are neither illustratednor described.

As illustrated in FIG. 10, in the substrate processing apparatus, apressure sensor 31 for detecting an internal pressure of a pipe isinstalled in a pipe which interconnects the cooling gas exhaust device356 and the radiator 357 of the exhaust unit 355. The pressure sensor 31may be installed at a position close to the radiator 357 in the pipewhich interconnects the cooling gas exhaust device 356 and the radiator357. By installing the pressure sensor 31 at the position close to theradiator 357, a pressure loss can be prevented from being caused in thecooling gas between the radiator 357 and the pressure sensor 31 underthe influence of a length of the pipe, a route of the pipe, a shape ofthe pipe, etc.

Similar to the substrate processing apparatus 1 described above withreference to the first embodiment, the control program 40 includes theprocess control unit 400, the temperature control unit 410, the processgas flow rate control unit 412, the drive control unit 414, the pressurecontrol unit 416, the process gas exhaust device control unit 418, thetemperature measurement unit 420, the cooling gas flow rate control unit422, and the temperature setting value storage unit 424. In FIG. 10,there are illustrated the process control unit 400 and the cooling gasflow rate control unit 422. The temperature control unit 410, theprocess gas flow rate control unit 412, the drive control unit 414, thepressure control unit 416, the process gas exhaust device control unit418, the temperature measurement unit 420 and the temperature settingvalue storage unit 424 are not shown in FIG. 10. Similar to thesubstrate processing apparatus 1 described in the first embodiment, thecontrol program is supplied to the control unit 2 via, for example, therecording medium 240 (see FIG. 4), loaded onto the memory 204, andexecuted.

The cooling gas flow rate control unit 422 includes a subtractor 4220, aPID computing unit 4222, a frequency converter 4224, and a frequencyindicator 4226. A pressure target value S is inputted from the processcontrol unit 400 to the subtractor 4220. In this regard, the pressuretarget value S is set in advance such that the center side of the wafer12 is maintained at a process temperature and the periphery side of thewafer 12 is maintained at a temperature lower than the processtemperature. In addition to the pressure target value S, a pressurevalue A measured by the pressure sensor 31 is inputted to the subtractor4220. The subtractor 4220 outputs a deviation D which is obtained bysubtracting the pressure value A from the pressure target value S.

The deviation D is inputted to the PID computing unit 4222. In the PIDcomputing unit 4222, PID computation is performed based on the inputdeviation D and an operation amount X is calculated. The calculatedoperation amount X is inputted to the frequency converter 4224 and isconverted to a frequency W in the frequency converter 4224. Thefrequency W is outputted from the frequency converter 4224. Theoutputted frequency W is inputted to the inverter 384 so that thefrequency of the cooling gas exhaust device 356 (the revolution-numberof a blower) is changed.

The pressure value A from the pressure sensor 31 is inputted to thesubtractor 4220 either at all times or at a specified time interval.Based on the pressure value A, the control of the frequency of thecooling gas exhaust device 356 is continuously executed such that thedeviation D between the pressure target value S (the pressure targetvalue in an upstream position of the exhaust path 354, specifically, thecooling gas exhaust device 356) and the pressure value A becomes 0. Inthis manner, the frequency of the cooling gas exhaust device 356 iscontrolled via the inverter 384 so that the deviation D between thepressure value A measured by the pressure sensor 31 and thepredetermined pressure target value S is eliminated. As such, thefrequency controlled so as to eliminate the deviation D isfeedback-controlled as the frequency for the case where the deviation is0. Based on the value after the feedback, the cooling gas flow ratecontrol unit 422 controls the flow rate of the cooling gas.

Instead of computing the frequency W in the PID computing unit 4222, thefrequency of the cooling gas exhaust device 356 may be changed byinputting a frequency setting value T from the process control unit 400to the frequency indicator 4226 and inputting a frequency W from thefrequency indicator 4226 to the inverter 384. The frequency settingvalue T may be changed by allowing a user to manipulate thedisplay/input unit 22 (see FIG. 4).

By performing the aforementioned control, the thickness of the filmformed on the wafer 12 can be prevented from being non-uniform due tothe change in the flow rate of the cooling medium flowing through thecooling gas flow path 352, even if there is a variation or a change inthe exhaust pressure of the facility connected to the exhaust hole 358.

In the substrate processing apparatus according to the fourthembodiment, the same control as used in the first embodiment, the secondembodiment, and the third embodiment is applied to the heating controland the process gas supply control executed by the control unit 2. Thus,in the fourth embodiment, it is possible to obtain the same effects asdescribed in the first embodiment, the second embodiment, and the thirdembodiment, even if there is a variation or a change in the exhaustpressure of the facility connected to the exhaust hole 358.

Fifth Embodiment

Next, a fifth embodiment of the present disclosure is described below.

FIG. 11 is a view illustrating a configuration of a substrate processingapparatus according to a fifth embodiment of the present disclosure. Inthe substrate processing apparatus according to the fourth embodiment sdescribed above, the control unit 2 controls the cooling gas exhaustdevice 356 based on the pressure value detected by the pressure sensor31 used as a pressure detector. In contrast, the substrate processingapparatus according to the fifth embodiment is configured to adjust thetarget pressure setting value (the pressure target value) in the exhaustpath 354 based on the pressure value detected by the pressure sensor 31and the temperature difference between the center side and the peripheryside of the target wafer 12 (hereinafter referred to as a “temperaturedistribution”). Some of the components identical with those of thesubstrate processing apparatus 1 in the first embodiment are neitherillustrated nor described.

The control program 40 used in the fifth embodiment includes the processcontrol unit 400, the temperature control unit 410, the process gas flowrate control unit 412, the drive control unit 414, the pressure controlunit 416, the process gas exhaust device control unit 418, thetemperature measurement unit 420, the cooling gas flow rate control unit422, and the temperature setting value storage unit 424. FIG. 11illustrates the process control unit 400, the temperature control unit410, the cooling gas flow rate control unit 422, and the temperaturesetting value storage unit 424. The process gas flow rate control unit412, the drive control unit 414, the pressure control unit 416, theprocess gas exhaust device control unit 418, and the temperaturemeasurement unit 420 are not shown in FIG. 11. Similar to the substrateprocessing apparatus 1 of the first embodiment, the control program issupplied to the control unit 2 via, for example, the recording medium240 (see FIG. 4), loaded onto the memory 204, and is executed.

The temperature control unit 410 includes a pressure setting valueadjustment unit 4102. The pressure setting value adjustment unit 4102calculates and sets a desired temperature distribution of the wafer 12using a correlation table of film thicknesses and temperaturedistributions previously registered in the temperature setting valuestorage unit 424.

The pressure setting value adjustment unit 4102 compares the temperaturedetected by the temperature measurement device 372 with the temperaturedistribution registered in the temperature setting value storage unit424, and calculates a pressure setting value in the upstream position ofthe cooling gas exhaust device 356, which makes the temperaturedistribution of the wafer 12 become a preset distribution. Then, thepressure setting value adjustment unit 4102 sends the pressure settingvalue to the cooling gas flow rate control unit 422 via the processcontrol unit 400. Instead of sending the pressure setting value from thepressure setting value adjustment unit 4102 to the cooling gas flow ratecontrol unit 422 via the process control unit 400, it may be possible todirectly send the pressure setting value from the pressure setting valueadjustment unit 4102 to the cooling gas flow rate control unit 422.

The control of the cooling gas exhaust device 356 pursuant to sendingthe pressure setting value from the pressure setting value adjustmentunit 4102 is executed until the temperature distribution becomes apreset value. For example, PID computation is used as in the fourthembodiment described above. By setting a PID constant, it is possible torealize rapid and stable temperature control while excessive temperaturefluctuation is suppressed. Further, the temperature control unit 410including the pressure setting value adjustment unit 4102 controls thepressure in the upstream position of the cooling gas exhaust device 356by presenting the pressure setting value to the cooling gas exhaustdevice 356 and adjusts the target pressure setting value, based on thetemperature detected by the temperature measurement device 372 and thetemperature distribution set by the pressure setting value adjustmentunit 4102.

FIG. 12 illustrates an example of the calculation of the pressuresetting value performed by the pressure setting value adjustment unit4102. Prior to the calculation, the pressure setting valuescorresponding to the respective temperature distribution values of thewafer 12 are previously registered, for example, in the temperaturesetting value storage unit 424. Correlation table data of the pressuresetting values and the temperature distribution values are acquired andinputted.

As illustrated in FIG. 12, when a pressure setting value P1 at atemperature distribution value of T1, a pressure setting value P2 at atemperature distribution value of T2, and a pressure setting value P3 ata temperature distribution value of T3 are registered for thetemperature distribution values having a relationship of T1<T2<T3, if itis intended to obtain a desired temperature distribution value T0, it ispossible to find a pressure setting value corresponding to the desiredtemperature distribution value T0 by performing linear interpolationwith the temperature distribution values (T1 and T2 in the example ofFIG. 12) which interposes T0 therebetween. The pressure setting valuefound in the aforementioned manner is set as the pressure target value Sdescribed in the fourth embodiment. The control of the frequency of thecooling gas exhaust device 356 is executed such that the deviation Dbetween the pressure target value and the pressure value A measured bythe pressure sensor 31 becomes 0.

In the substrate processing apparatus according to the fifth embodiment,the same control as used in the first embodiment, the second embodiment,and the third embodiment is applied to the heating control and theprocess gas supply control executed by the control unit 2.

FIG. 13 is a view illustrating the temperature difference between thecenter side and the periphery side of the wafer 12 when the secondcontrol described in the second embodiment and the third embodiment isexecuted at different pressure setting values. As illustrated in FIG.13, if the pressure setting value increases, the temperature differencebetween the center side and the periphery side of the wafer 12 when theoperation of the cooling device is stopped increases. Accordingly, thecalculation of the pressure setting value illustrated in FIG. 12 may beapplied to the calculation of the pressure setting value in the fifthembodiment when executing the second control described in the secondembodiment and the third embodiment.

As described above, in the fifth embodiment, the target temperaturedistribution can be realized by setting the exhaust pressurecorresponding to the target temperature distribution value (thetemperature difference between the center side and the periphery side ofthe wafer 12). Furthermore, in the fifth embodiment, it is possible toobtain the same effects as described in the first embodiment, the secondembodiment, and the third embodiment, even if there is a variation or achange in the exhaust pressure of the facility connected to the exhausthole 358.

Sixth Embodiment

Next, a sixth embodiment of the present disclosure is described below.

In the second embodiment as described above, the heating control and theprocess gas supply control are improved to switch the first control (inwhich the cooling device cools the wafer while the heating device heatsthe wafer from the periphery side of the wafer) and the second control(in which the operation of at least the cooling device is stopped afterthe first control) during the process gas supply period. As a result, bysupplying the process gas during the execution of the second control,the effect of cooling the periphery portion of the waver can be achievedmore efficiently than in the first embodiment. In the sixth embodiment,the heating control is further improved so as to further enhancedecreasing the temperature of the wafer periphery portion.

FIG. 14 is a timing chart illustrating an example of the heating controland the process gas supply control of a substrate processing apparatusaccording to the sixth embodiment of the present disclosure. Since theconfiguration of the substrate processing apparatus 1 according to thesixth embodiment is the same as the configuration of the substrateprocessing apparatus 1 according to the first embodiment, thedescriptions for the substrate processing apparatus 1 are omitted.

As illustrated in FIG. 14, the control unit 2 first operates the heatingdevice (specifically, the temperature control part 320 of the heater 32)so that the temperature detected by the internal temperature sensor 324is increased from a standby temperature to a process temperature. As aresult, the temperature of the center side of the wafer 12 is increasedto a preset temperature. If the temperature detected by the internaltemperature sensor 324 reaches the process temperature (if thetemperature of the center side of the wafer 12 reaches the presettemperature), the control unit 2 starts operation of the cooling device(starts the third control).

In the sixth embodiment of the present disclosure, if the temperaturedetected by the internal temperature sensor 324 is stabilized at theprocess temperature (if the temperature of the center side of the wafer12 is stabilized at the preset temperature), the control unit 2 stopsthe operation of the cooling device and operates the process gas flowrate control device 374. Further, the control unit 2 operates theprocess gas flow rate control device 374 so as to decrease the presettemperature at a specific temperature decrease speed and starts thesupply of the process gas into the process chamber 3 (the interior ofthe outer tube 360).

As described in the second embodiment of the present disclosure, in thesixth embodiment, the temperature difference between the center side andthe periphery side of the wafer 12 increases for a specific time periodafter the operation of the cooling device is stopped. This means thatthe temperature of the periphery side of the wafer 12 decreases largelywhen compared with the temperature of the center side. As such, if theoperation of the cooling device is stopped from the operating state, thetemperature of the periphery side of the wafer is temporarily decreasedfaster than the temperature of the center side of the wafer. The reasonis the same as that of the second embodiment. Thus, the descriptions forthe foregoing reasons are omitted.

Accordingly, in the sixth embodiment, when the supply of the process gasinto the process chamber 3 is started by operating the process gas flowrate control device 374, the operation of the cooling device is stoppedand the preset temperature of the heating device is actively decreased.Thus, as compared with the second embodiment, the temperature detectedby the internal temperature sensor 324 can be decreased. The output ofthe heating device decreases along with the decrease of the temperature.The temperature of the periphery side of the wafer 12 can be largelydecreased when compared with the temperature of the center side.Therefore, a large temperature difference can be caused between thecenter side and the periphery side of the wafer 12. Thus, thicknessuniformity of the film formed on the wafer can be controlled effectivelyand the film thickness uniformity can be further improved.

Descriptions with reference to FIG. 14 follow. In the followingdescriptions, the control in which the temperature detected by theinternal temperature sensor 324 (the temperature of the center side ofthe wafer) is decreased to be lower than the process temperature bysetting the preset temperature of the heating device at a temperatureequal to or higher than an activation temperature of the used processgas and to be lower than the process temperature during the time periodin which the operation of at least the cooling device is stopped afterthe above first control while the process gas is supplied (the timeperiod indicated as “DEPO” in FIG. 14) will be referred to as “thirdcontrol”.

[Start Timing of Third Control]

The start timing of the third control is the same as the start timing ofthe second control in the second embodiment.

The execution time period of the first control is set to be apredetermined time period (a time period in which the temperaturedifference between the center side and the periphery side of the wafer12 reaches a desired temperature by the first control while thetemperature of the center side of the wafer 12 is maintained to be aspecific temperature). After executing the first control for the timeperiod, the third control is started.

In the sixth embodiment, similar to the second embodiment, the thirdcontrol is started before the temperature of the periphery side of thewafer 12 decreases to be lower than the temperature of the center side.Thus, similar to the second embodiment, in the sixth embodiment, acooling device whose cooling performance is lower than that of the firstembodiment can be employed. In addition, in the sixth embodiment, thecooling device is not continuously operated for a long period of time.Thus, the load of the heating device due to the cooling is reduced.Accordingly, contrary to the above descriptions, the cooling performanceof the cooling device can be improved, the periphery side of the wafer12 can be cooled in a short period of time, and the execution timeperiod of the first control can be shortened.

[Execution Time Period of Third Control]

As illustrated in FIG. 14, the third control is executed for a period oftime after the first control. During the execution of the third control,the process gas flow rate control device 374 is operated to supply theprocess gas into the process chamber 3.

The execution time period of the third control is determined in advanceby experiments or the like. Although operation of the cooling device isstopped, temperature in the outer tube 360 decreases due to natural heatdissipation. Thus, the control unit 2 controls the heating device sothat the temperature detected by the internal temperature sensor 324 iscorresponded to be at the preset temperature which decreases with aconstant gradient (temperature decrease rate). As compared with thesecond control, an amount of heat applied by the heating device isreduced as much as the decrease of the preset temperature, and thus, thetemperature decrease due to the natural heat dissipation increases. Asdescribed above, the heating device heats the wafer 12 from theperiphery side of the wafer 12. Therefore, while the cooling device isstopped, the temperature of the wafer 12 is more easily increased at itsperiphery side than at its center side. Accordingly, when the timeperiod, in which the temperature of the periphery side of the waferdecreases faster than the temperature of the center side of the wafer,is elapsed after the cooling device is stopped, the temperaturedifference between the center side and the periphery side becomessmaller. Eventually, the temperature of the periphery side exceeds thetemperature of the center side. Thus, the time period, in which adifference equal to or larger than a specific temperature can begenerated between the center side and the periphery side of the wafer12, namely, the time period, in which the temperature of the peripheryside can be maintained to be lower than the temperature of the centerside by a specific temperature or more, is measured in advance byexperiments or the like. The time period as measured above is set as theexecution time period of the third control.

If a desired thickness for a film cannot be formed during the executiontime period of the third control, that is, if the execution time periodof the third control fails to meet a specified process time period, thecooling device is operated again to execute the first control. Thepreset temperature is increased to the process temperature. Thetemperatures of the center side and the periphery side of the wafer 12are set to preset temperatures (the temperature difference between thecenter side and the periphery side of the wafer 12 is set to a presettemperature). Thereafter, the operation of the cooling device is stoppedagain to execute the third control and the supply of the process gas isperformed. In this manner, a specific process time period can be securedby alternately and repeatedly executing the first control and the thirdcontrol a predetermined number of times.

In FIG. 14, a start timing of the third control (a timing at which theoperation of the cooling device is stopped) and a start timing of thesupply of the process gas are brought into coincidence with each other.An end timing of the third control (a timing at which the operation ofthe cooling device is resumed) and an end timing of the supply of theprocess gas are brought into coincidence with each other. However, theprocess gas needs to be supplied at least for a certain period of timewhile the third control is performed. Accordingly, for example, thestart timing of the supply of the process gas may be set to be laterthan the start timing of the third control. Furthermore, the end timingof the supply of the process gas may be set to be earlier than the endtiming of the third control. As such, if the process gas is supplied fora specified time period while the third control is executed at leastafter the first control is switched to the third control, efficientcooling effect for the periphery side of the wafer by using the thirdcontrol can be achieved. However, to secure a process time period, theexecution time period of the third control and the supply time of theprocess gas may be brought into coincidence with each other.

Although the preset temperature is decreased from the processtemperature in the third control, the preset temperature may bedecreased from a temperature higher than the process temperature. In thethird control, the preset temperature may be decreased only in aspecific heating region so that the reduction gradient of the presettemperature can be used as an inter-wafer film thickness adjustmentvalue.

While the first to sixth embodiments have been described above, therespective embodiments as described above, modifications thereof, andapplications thereof may be suitably combined with one another. Theeffects of the respective embodiments may also be obtained incombination.

INDUSTRIAL USE OF THE PRESENT DISCLOSURE

As described above, the present disclosure can be used in a substrateprocessing apparatus, a substrate processing method, a semiconductordevice manufacturing method, and a control program, which are capable ofcontrolling thickness uniformity of a film formed on a substrate.

EXPLANATION OF REFERENCE NUMERALS

-   -   1: substrate processing apparatus    -   12: wafer (substrate)    -   14: boat    -   100: cassette delivery unit    -   102: cassette stocker    -   106: wafer transfer machine    -   108: boat elevator    -   490: wafer cassette    -   2: control unit    -   22: display/input unit    -   200: CPU    -   204: memory    -   24: recording unit    -   240: recording medium    -   40: control program    -   400: process control unit    -   410: temperature control unit    -   4102: pressure setting value adjustment unit    -   412: process gas flow rate control unit    -   414: drive control unit    -   416: pressure control unit    -   418: process gas exhaust device control unit    -   420: temperature measurement unit    -   422: cooling gas flow rate control unit    -   4220: subtractor    -   4222: PID computing unit    -   4224: frequency converter    -   4226: frequency indicator    -   424: temperature setting value storage unit    -   3: process chamber    -   300: heat insulator    -   31: pressure sensor    -   32: heater    -   320: temperature control part    -   322, 324: temperature sensor    -   340: gas supply nozzle    -   344: lid member of a furnace port    -   346: exhaust pipe    -   348: rotation shaft    -   350: manifold    -   351: O-ring    -   352: cooling gas flow path    -   353: intake hole    -   354: exhaust path    -   355: exhaust unit    -   356: cooling gas exhaust device    -   357: radiator    -   358: exhaust hole    -   359: shutter    -   360: outer tube    -   362: inner tube    -   370: temperature control device    -   372: temperature measurement device    -   374: MFC    -   376: EC    -   378: PS    -   380: APC    -   382: EP    -   384: inverter

1. A substrate processing apparatus, comprising: a process chamber intowhich a substrate is transferred; a heating device which heats thesubstrate, transferred into the process chamber, from a periphery sideof the substrate; a cooling device which cools the substrate,transferred into the process chamber, from the periphery side of thesubstrate; a process gas supply unit which supplies a process gas intothe process chamber; and a control unit which controls each of theheating device, the cooling device, and the process gas supply unit toform a predetermined film on the substrate by executing a first control,in which the heating device and the cooling device are operated;executing a second control, in which operation of at least the coolingdevice is stopped, after the first control; and supplying the processgas into the process chamber by operating the process gas supply unit atleast during execution of the second control.
 2. The substrateprocessing apparatus of claim 1, wherein the control unit controls theprocess gas supply unit to supply the process gas into the processchamber, in a specific time period at least after the first control isswitched to the second control.
 3. The substrate processing apparatus ofclaim 1, wherein the control unit controls the process gas supply unitto start supplying the process gas into the process chamber when thefirst control is being executed.
 4. The substrate processing apparatusof claim 1, wherein the control unit controls the process gas supplyunit to supply the process gas into the process chamber concurrentlywith a timing of starting the second control.
 5. The substrateprocessing apparatus of claim 1, wherein the control unit controls eachof the heating device, the cooling device, and the process gas supplyunit to alternately and repeatedly execute the first control and thesecond control a predetermined number of times.
 6. (canceled) 7.(canceled)
 8. (canceled)
 9. A semiconductor device manufacturing method,comprising: a first process in which a substrate is transferred into aprocess chamber; a second process in which the substrate transferredinto the process chamber is cooled from a periphery side of thesubstrate by a cooling device while the substrate is heated from theperiphery side of the substrate by a heating device; a third process inwhich a process gas supply unit is operated to start supplying a processgas into the process chamber during execution of the second process; anda fourth process in which operation of the cooling device is stoppedwhile the process gas is supplied in the third process after the secondprocess ends.
 10. (canceled)
 11. A non-transitory computer-readablerecording medium that records a control program for causing a computerto execute: a first process in which a substrate is transferred into aprocess chamber; a second process in which the substrate transferredinto the process chamber is cooled from a periphery side of thesubstrate by a cooling device while the substrate is heated from theperiphery side of the substrate by a heating device; a third process inwhich a process gas supply unit is operated to start supplying a processgas into the process chamber during execution of the second process; anda fourth process in which operation of the cooling device is stoppedwhile the process gas is supplied by the third process, after the secondprocess ends.
 12. (canceled)
 13. A substrate processing apparatus,comprising: a process chamber into which a substrate is transferred; aheating device which heats the substrate, transferred into the processchamber, from a periphery side of the substrate; a cooling device whichcools the substrate, transferred into the process chamber, from theperiphery side of the substrate; a process gas supply unit whichsupplies a process gas into the process chamber; and a control unitwhich controls each of the heating device, the cooling device, and theprocess gas supply unit to form a predetermined film on the substrate byexecuting a first control in which the heating device and the coolingdevice are operated; executing a third control in which operation of atleast the cooling device is stopped after the first control and theheating device is controlled by setting a setting of the heating deviceto be lower than a process temperature; and supplying the process gasinto the process chamber by operating the process gas supply unit atleast during execution of the third control.
 14. The substrateprocessing apparatus of claim 1, wherein the control unit controls theprocess gas supply unit to supply the process gas into the processchamber at a timing that is different from a timing of starting thesecond control.
 15. The substrate processing apparatus of claim 1,further comprising a temperature control part which controls at least atemperature of the substrate, wherein the control unit performs afeedback-control on the temperature control part based on a temperaturedetected by a temperature detection device which is installed at aposition corresponding to the temperature control part.
 16. Thesubstrate processing apparatus of claim 13, wherein the control unitcontrols the process gas supply unit to supply the process gas into theprocess chamber concurrently with a timing of starting the thirdcontrol.
 17. The substrate processing apparatus of claim 13, wherein thecontrol unit controls the process gas supply unit to supply the processgas into the process chamber at a timing that is different from a timingof starting the third control.